The invention relates to a metathesis process for the conversion of olefines as well as a catalyst to be applied therein.
The metathesis or disproportionation of olefines refers to a reaction, in which one or more olefines are converted into olefines having a different molecular weight. The olefine may be disproportionated with itself into olefines having a higher molecular weight and into olefines having a lower molecular weight. In this case, the reaction may be called a "self-disproportionation". Two different olefines can also be converted into other olefines by means of the metathesis reaction.
In order to function, the metathesis reactions of olefines require a catalyst system, which includes a transition metal compound, often a cocatalyst, and sometimes also a compound which acts as a promoter. Catalyst systems based on tungsten and molybdenum are especially efficient. Such catalysts generally comprise a tungsten or molybdenum oxide on an inorganic carrier, such as silica or alumina.
It is known to add to such catalysts different substances which act as promoters. Thus, for example according to the EP Publication No. 152112, a titanium oxide or titanium-containing substances are added to the surface of the catalyst as a promoter. The U.S. Pat. No. 4,559,320, describes the use of a tungsten catalyst on a silica carrier, to which catalyst is also added a magnesium oxide.